"It was even more intense than sitting on a roller coaster," one passenger told the paper. The plane "was jolted for at least two minutes. I was thrown up very high."

He said there was no announcement warning people to fasten seat belts, adding that some passengers were thrown out of their seats and struck the overhead lockers.

The incident came one day after a United Airlines flight encountered severe turbulence that injured five people. The Federal Aviation Administration and the National Transportation Safety Board are investigating United Flight 1676 from Denver to Billings, Mont. That incident happened shortly after noon Monday while the jet was at 34,000 feet in northern Wyoming.

Three flight attendants and two passengers were taken to the hospital after the jet landed in Billings. One flight attendant was admitted, the other injured were treated and released.